Shoe system with a resilient shoe insert

ABSTRACT

The method is for using a shoe system having a resilient shoe insert. A shoe ( 300 ) has a shoe insert ( 500 ) disposed inside the shoe. The insert has an upper leg ( 506 ) and a lower leg ( 514 ) connected by a front end ( 502 ) with a curvature ( 512 ). The legs ( 506, 514 ) have a concave segments ( 510, 518 ) and end points ( 520, 522 ), respectively; A load is put on the insert to compress the end points towards one another. This shortens the effective length of the legs ( 506, 514 ) because the legs are in contact at a contact segment ( 524 ). This makes the insert stiffer the more it is compressed. The effective length of the legs is shorter at the outside ( 530 ) compared to the inside ( 532 ) so that the outside is stiffer than the inside.

TECHNICAL FIELD

The present invention relates to a resilient shoe spring system that isintergrated with a shoe system.

BACKGROUND AND SUMMARY OF THE INVENTION

Users and developers of elastic shoes and shoe soles are confronted withthe problem of back injury and releasing the stored energy in the shoesole in a manner which improves walking and running economy while at thesame time achieving adequate bio-mechanical shoe stability andcushioning. Many shoe manufacturers have concentrated their effort onchock absorption by permanently increasing the thickness of the shoesole. This has resulted in a slight change of the angle between theankle and the foot that may weaken the tendons of the foot. This changeof the angle may also lead to instability and reduced bio-mechanicaleffect.

Many efforts have been made to develop an effective spring mechanism forshoes or shoe soles. However, the earlier proposed spring designs forshoe soles have not been entirely satisfactory. Despite many elaborateshoe sole solutions, back injuries and other injuries are still commondue to poorly designed shoes. Injuries due to poor shoe designs areparticularly common in sports and heavy duty work activities.

One important function of a shoe, such as a running shoe, is to protectthe foot from the stresses of running. The forces and motions that occurin different sports vary greatly. Because of these differences it isimportant that active participation in varied sports require variedshoes. For example, tennis and other racquet sports require muchside-to-side motion and the shoe must provide lateral stability. If theshoe is unstable and has high heel elevation when the athlete is movingfrom one side to another the likelihood is great the athlete may sufferan ankle sprain. The majority of conventional shoes are not welldesigned. Some of insufficiencies of the current shoe designs may beovercome by the present invention.

The method and shoe system of the present invention provide a solutionto the above-mentioned problems. More particularly, the method is forusing a shoe system having a resilient shoe insert. A shoe has a shoeinsert disposed inside the shoe. The insert has an upper leg and a lowerleg connected by a front end with a curvature. The upper and lower legs506 have a concave segments and end points. A load is put on the insertto compress the end points towards one another. This shortens theeffective length of the legs because the legs are in contact at acontact segment. This makes the insert stiffer the more it iscompressed. The effective length of the legs is shorter at the outsidecompared to the inside so that the outside is stiffer than the inside.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a shoe insert of the present invention;

FIG. 2 is a side view of a shoe adapted to receive the shoe insert ofFIG. 1;

FIG. 3 is a rear view of the shoe in a vertical position along line 3-3of FIG. 2 with the shoe insert of FIG. 1 placed inside the shoe;

FIG. 4 is a rear view of the shoe along line 3-3 of FIG. 2 when theankle is disposed in an inwardly sloping position;

FIG. 5 is a side view of a person standing straight up on the shoe ofthe present invention;

FIG. 6 is a side view of a person standing on the shoe and leaningforward;

FIG. 7 is a side view of an alternative embodiment of the shoe insert ofthe present invention;

FIG. 8 is a top view of the shoe insert;

FIG. 9. is a top view of a second embodiment of a shoe insert for theright shoe;

FIG. 10 is a top view of the second embodiment of the shoe insert forthe left shoe;

FIG. 11 is a bottom view of a third embodiment of a shoe insert;

FIG. 12 is a side view of a fourth embodiment of a shoe insert;

FIG. 13 is a side view of a fifth embodiment of a shoe insert integratedwith a shoe sole;

FIG. 14 is a side view of the fifth embodiment of the shoe insert in acompressed position;

FIGS. 15A-D are schematic flow diagrams of a pressing technique formanufacturing the shoe insert;

FIG. 16 is a top view of a sixth embodiment of the shoe insert of thepresent invention;

FIG. 17 a is a side view of the sixth embodiment in a relaxednon-compressed position; FIG. 17 b is a side view of the sixthembodiment in a semi-compressed position so that the upper leg is incontact with the lower leg;

FIG. 17 c is a side view of the sixth embodiment in a compressedposition; FIG. 18 is a top view of the sixth embodiment showing thevaried effective lengths of the leg members; and

FIG. 19 is a schematic graphic illustration of a load L on the shoeinsert of the present invention.

DETAILED DESCRIPTION

With reference to FIGS. 1-8, the present invention is a shoe system 10having a resilient shoe insert 11 including a stiff first support member12 that may be made of a carbon fiber reinforced composite material orany other suitable material that is relatively stiff. The first member12 has a flexible and bendable fore end 14 and a stiff aft end 16. Thefore end 14 has a cavity portion 18 that terminates in a slightlyupwardly curved end section 20. It is to be understood that the fore endis preferably made of a flexible and bendable material that may be cutto size by a pair of scissors to tailor the shape of the fore end 14 tothe shape of the shoe system and the foot. Another reason for using theflexible material at the fore end 14 is so that the toes of the foot mayfully cooperate with the fore end 14 when walking and moving about.

The stiff aft end 16 has a cavity portion 22 that terminates in aslightly upwardly curved end section 24. A stiff middle section 26 ofthe member 12 is convex shaped relative to the concave cavity portions18, 22. A holder mechanism 26 is attached to an underside 28 of thefirst member 12. The holder mechanism 26 includes a short end wall 30that is perpendicular to the member 12 and a long support wall 32 thatis perpendicularly attached to the end wall 30 to that the underside 28,the end wall 30 and the support wall 32 define a receiving pocket 34that is facing the aft end 16. Preferably, the end wall 30 is attachedto the underside 28 on the first member 12 at a point 29 that is at afront-end portion of the middle section 26. In the preferred embodiment,the first member 12 is stiff all the way from the place of attachment atthe point 29 of the end wall 30 to the end section 24 and bendable fromthe point 29 to the end section 20.

A second member 36 has a fore end 38 that is insertable into thereceiving pocket 34. More particularly, the second member has the foreend 38 and an opposite aft end 40. The force end 38 has a slightlydownwardly curved end section 42 and the aft end 49 has an upwardlycurved end section 44 so that the second member 36 is somewhat S-curved.When the second member 36 is inserted into the receiving pocket 34, theend section 44 is aligned with the end section 24 of the first member 12so that a gap 46 is formed between the first member 12 and the secondmember 36.

An important feature of the present invention is that the second member36 is springy and resilient while the first member 12 is generally stiffexcept for a bendable toe portion. As is explained below, a heavierperson may select a stiffer second member than a lighter person toprevent the second member 36 from abutting or resting against the firstmember 12 when the heavier person is standing on the first member 12with the second member 36 inserted into the receiving pocket 34.Preferably, the second member 36 should be sufficiently stiff so thatthe second member 36 does not bottom out even though the person isactively using the shoe insert 11 disposed in the shoe. For example,when a person is standing straight up (as is shown in FIG. 5) so thatthe shoe insert 11 is subjected to the greatest weight, the first member12 form a minimum angle alpha relative to the second member 36 but theangle should not be zero. The angle alpha increases when the personbends his/her knees or leans forward, as is shown in FIG. 6, so that anincreasing amount of the body is supported by the front portion of thefoot and less weight is exerted upon the second member 36. It is alsopreferred that the stiffness and the shape of the second member 36 aresuch that the first member 12 does not bottom out even though the personis jumping or actively using a shoe 48.

Other factors that determine what stiffness to use for the second member36 include the type of activity the shoe is going to be used for andwhether the walking/running surface is hard, soft and uneven. The shapeof the second member 36 may also be varied depending on the needs of theuser. For example, a second member having a more bent fore end creates abigger gap 46 between the second member and the first member when thesecond member is inserted into the holder 32. A bigger gap 46 may reducethe risk of bottoming out and also changes the angle between the footand the ankle.

Because the first member 12 is stiff, the shape of the first member ismaintained and the foot is provided a full support although the secondmember 36 may move relative to the first member 12. In other words, thefirst member 12 provides good support to the foot although the secondmember 36 may be compressed against the first member 12 and laterpermitted to move back to the relaxed expanded position depending uponhow the shoe is used in, for example, a sport activity.

As best shown in FIG. 2, the shoe 48 may have a preformed shoe sole 50that has an upper surface 52 that is shaped to snugly receive the shoeinsert 11. The shoe 48 has a heel section 51 and a toe portion 53. Theshoe sole 50 is preferably made of a flexible material such as rubber orplastic. The upper surface 52 has an upwardly curved front portion 54, aconvex middle portion 56 and a slightly upwardly curved aft portion 58to support the sections 20, 26 and 24, respectively, of the first member12.

An important feature is that the shoe sole defines an angular curvedgroove 60 that is dimensioned to receive the second member 36. Thegroove 60 extends backwardly and angularly downwardly towards a heel 62of the shoe 48. A triangular wedge 64 is disposed between the uppersurface 52 and the groove 60. The wedge 64 is removably attached to thesole 50 so that the wedge 64 easily be removed to make it convenient toinsert and remove, particularly, the second member 36 of the shoe insert11. The wedge 64 is made of a very flexible material so when the secondmember 36 is urged towards the first member 12 by the weight of theuser, the wedge 64 is deformed and compressed accordingly.

The shoe 48 may also be used with the shoe insert 11 placed on the uppersurface 52 but with the wedge 64 removed. An one-way valve 66 isattached to a back end 68 of the shoe 48. A channel 70 may be defined inthe shoe sole 50 so that the valve 66 is in fluid communication with aspace 72 that is formed between the first member 12 and the secondmember 36. Of course, the wedge 64 may extend all the way back to thesection 58 of the shoe sole 50 so that there is no need for a channel.

When the second member 36 is pressed towards the first member 12 so thatthe shoe insert 11 is in a compressed position, an over pressure isformed in the space 72 that may flow into the channel 70 and out throughthe valve 66 to provide good mechanical ventilation inside the shoe. Anyunder pressure that may be formed in the space 72 when the second member36 is permitted to move from the compressed position back to itsoriginal expanded position away from the first member 12 may beequalized by sucking in air from an upper part 74 of the shoe 48 such asthe opening 76 or the open areas adjacent to the shoe laces 78. Itshould be understood that the valve 66 may also be a two-way valve sothat the valve may be used to compensate for both over-pressure andunder-pressure in the space 72. In this way, the valve 66 may functionto circulate and possibly bring in or suck cool air into the inside ofthe shoe when the second member 36 is permitted to expand from thecompressed position. A filter 79 may also be placed in the valve 66 toprevent dust and other undesirable particle from entering into theinside of the shoe 48 when the shoe inlet 11 is expanding.

As best shown in FIG. 3, the first member 12 and the second member 36are substantially parallel when a person is standing straight up withoutleaning sideways. The first member 12 may have vertical sidewalls 81, 83to prevent the foot from sliding sideways and put undue pressure on thesidewall of the shoe. However, when the person moves in a sidewaysdirection so that an ankle 90 is in an inclined position, the weightdistribution of the shoe may be uneven, as shown in FIG. 4, so that thesecond member 36 is twisted slightly relative to the stiff first member12 to create a torsion force about an outside portion 82 of the secondmember 36. The second member 36 may have a first thickness d₁ on aninside portion 80 and a second thickness d₂ on the outside portion 82.The second thickness d₂ is greater than the first thickness d₁ so thatthe second member 36 is only permitted to twist relative to the stifffirst member 12 when the ankle 90 is leaned inwardly, as shown in FIG.4, if the shoe 48 shown is a shoe for the right foot. In other words,the second thickness at the outside portion 82 is sufficiently thick tomake the outside portion 82 of the second member 36 rigid enough toprevent any relative movement between the first member 12 and the secondmember 36 at the outside portion 82. Because the inside portion 80 istwistable, there is less need to bend the ankle relative to the foot,thus exposing the ankle to less strain, when the person is standing withthe legs wide apart. For example, it is common to stand with the legswide apart when waiting to return a serve in tennis. Another situationthat may put extra strain on the ankle is when running along a surfacethat is sloping sideways. The twisting of the inside portion 80generally results in less risk of straining the foot because the anglechange between the ankle and the foot as a result of, leaning the ankleinwardly is reduced.

FIG. 7 shows an alternative embodiment of the present invention. Theshoe insert 100 includes an extended back support section 102 thatextends above the heel of the foot to partly protect the Achilles tendonand the heel of the foot. The support section 102 reduces any excessiverubbing between the heel of the foot and the rear inside wall of theshoe. Excessive rubbing may cause blisters as the shoe insert 11 iscompressed and expanded. Similar to the shoe insert 11, the shoe insert100 has a stiff first member 104, a resilient second member 106 and abendable and flexible fore end 108 that may terminate at a toe portion109 that extends over the toes of the foot to protect the toes while thetoe portion 109 may follow the movement of the shoe insert. A resilientrubber pad may be adhered to a bottom side of the fore end 108 toprovide extra comfort. The first member 104 and the second member 106form an angle alpha therebetween. This embodiment is particularly usefulfor working shoes and other types of heavy-duty boots.

As best shown in FIG. 8, a transition area 77 between the first member12 and the soft and flexible fore end 14 may be a curved section that isformed according to the support area of the foot that is disposed behindthe toes.

FIG. 9 is a top view of a second embodiment of the shoe insert of thepresent invention. A shoe insert 200 has a transition area 202 (that isequivalent to the transition area 77 of FIG. 8) that extends at an angleso that a distance (x) at an inside 204 of the shoe insert 200 is longerthan a distance (y) at an outside 206. In other words, the flexiblemember is longer at the inside 204 than the outside 206 so that theinside 204 may flex (as shown in FIG. 4) while the outside 206 isrelatively stiff. Similarly, FIG. 10 shows a top view of a shoe insert210 for the left shoe that has a transition area 211 and an inside 212that has a length (x) that is longer than a length (y) of an inside 214.FIG. 11 is a bottom view of a third embodiment of the present invention.A shoe insert 216 has an angular transition area 218 in addition to aflexible member 220 that has a softer inside portion 222 and a stifferoutside portion 224. In the third embodiment, it is not necessary thatthe transition area extends at an angle because the inside portion 222is already softer than the outside portion 224. FIG. 12 is a side viewof a shoe insert 230 having a plurality of flexible members 232, 234,236 attached to an underside 238 of the shoe insert 230 so that both theresiliency and the resiliency on the inside and the outside may beadjusted to the specific needs of the user of the shoe insert 230.

FIGS. 13 and 14 show a fifth embodiment of the present invention. A shoe300 has a shoe sole 302 including an upper layer 303 with a shoe insert304 integrated with or built into the sole 302. The shoe 300 has a toeportion 330 and a heel portion 332 and shoe sole 302 has a bottom side305. The insert 304 has a relatively stiff upper segment 306 and abendable lower segment 308 that is attached to a lower side 310 of thesegment 306 at a mid-section 312 of the upper segment 306. The segment306 is, preferably, attached to a back piece 301 that is disposed at theupper segment 303 adjacent to a backside 309 of the shoe 300. The uppersegment 306 and the lower segment 308 have a space 307 definedtherebetween. The space 307 may be filled with air or a verycompressible and expandable material. The space 307 may be completely orpartially filled with a material. For example, the material may includesegments of an elastomeric material to change the spring characteristicsof the insert 304. Stiffer elastic segments may be used if the person isheavy and less segments or less stiff segments may be used if the personis relatively light.

An important feature is that the segment 306 is stiff and is attached tothe sole so that the segment 306 does not move relative to the shoealthough the lower segment 308 may move relative to the upper segment306. This means that a foot inserted into the shoe 300 remains in thesame position regardless of the flexural movements of the lower segment308. When the lower segment 308 is in an expanded unloaded position (seeFIG. 13) the distance between the upper segment 306 and a bottom side305 of the sole 302 is a distance (A). However, when the shoe 300 is putunder a load (L) (see FIG. 14), the lower segment 308 moves into acompressed position towards the upper segment 306 to reduce the distancebetween the upper segment 306 and the bottom side 310 to a distance (B)that is smaller than the distance (A). When the lower segment 308 is inthe compressed position, the segment 308 urges the upper segment 306upwardly into the expanded position.

An important feature of the present invention is that upper segment 306is disposed at a distance (X) from an upper rim 314 both when the lowersegment 308 is in the expanded position, as shown in FIG. 13, and in thecompressed position, as shown in FIG. 14. This means that there islittle risk of blisters on a foot 316 placed in the shoe 300 betweenthere is no relative movement between the foot 316 and the shoe 300.

With reference to FIGS. 15A-D, the shoe insert of the present inventionis preferably made by using a unique pressing method. The method relieson a tool 400 having a upper component 402 and a lower component 404.The component 402 has a cavity 406 defined therein that has the sameshape as the upper segment 306 and the component 404 has a cavity 408defined therein that has the same shape as the lower segment 308. Asbest shown in FIG. 15B, the components 404, 406 are separated from oneanother. A pre-impregnated upper component 410 is placed, as shown by anarrow A1, inside the cavity 406. The component 410 has an elongatefront-end portion 409 and an elongate back end portion 411 and a shapethat is similar to the shape of the cavity 406. A pre-impregnated lowercomponent 412 is placed in the cavity 408 and has a shape that issimilar to the shape of the cavity 408. Preferably, the components 410,412 and 414 are made of polymer composites such as carbon and/or glassfiber reinforcements that are impregnated with a suitable resin. Thecomponents may be fully or partly impregnated. Preferably, the toeportions of the components 410, 412 are partially impregnated to obtainan increased bendability. The resin could be a suitable thermoplastic,such as thermoplastic polyester, or a thermoset resin, such as epoxy. Ofcourse, other suitable polymers can also be used.

The component 412 has an elongate front-end portion 413 and an elongateback portion 415. A U-shaped third component 414 is placed betweencomponents 410, 412 to improve the physical properties of a finishedinsert 424. The component 414 has continuous fibers extending along theentire component 414 from one end of the U-shaped component to anopposite end of the component 414. Surprisingly, the component 414substantially reduces fiber breakage and other failure characteristicsof the insert 424. Preferably, a sandwich construction is used so thatthe stiffer carbon fibers may be placed on each side of the U-shapedcomponent 414 that is, preferably, made of the less stiff glass fibers.Glass fibers have better springing characteristics compared to carbonfibers due to the high fatigue resistance properties of glass fibers. Ingeneral, glass fibers are not as brittle as carbon fibers. Carbon fibersmay be used to partially or fully in the components 410, 412. However,carbon fibers may also be used on the inside of the component 414 in theform of carbon fiber tapes that extend from a back portion 411, 415,respectively, of the components 410, 412 towards a bottom 421 of thecomponent 414. More particularly, the component 414 has the bottom 421,an upper leg 416 and a lower leg 418. The upper leg 416 is placed alongan inside 420 of the back end portion 411 and the lower leg 418 isplaced along an inside 422 of the back portion 415. In this way, boththe upper leg 416 and the end portion 411 are placed inside an elongateback end 417 of the cavity 406 and the both the lower leg 418 and theback end portion 415 are placed inside an elongate back end 419 of thecavity 408. This means that the above described sandwich constructionmay be used on the legs 416, 418 of the components 410, 412 togetherwith the component 414. Preferably, the sandwich construction is notused for the portions 409, 413. A resilient filler piece 423 may beplaced between the legs 416, 418 prior to compression of the tool. Thehardness of the piece 423 may be adjusted depending upon the weight ofthe user. For example, a more rigid piece 423 may be used if the user isheavy and a softer piece 423 may be used if the user is relativelylightweight.

As best shown in the FIG. 15 c, when the components 410, 412 with thethird component 414 placed therebetween, are properly positioned in thetool components 402, 404, the components 402, 404 are moved towards oneanother, as shown by arrows A2 and A3. A pressure of between 2-40 bar isapplied to the components 402, 404 for several minutes and thetemperature is raised to between 100-250° C. to enable the resin of thecomponents 410, 412 to enable a thermoplastic resin to melt or athermoset resin to cure. The tool 400 may then be rapidly cooled beforethe components are removed from the tool 400.

When the components 410, 412, 414 are cured into an integrated shoeinsert 424, the tool components 402, 404 are separated from one anotherand the insert 424 is removed from the components 402, 404, as shown byan arrow A4 in FIG. 15D. The insert 424 is now ready to be integratedwith or built into a shoe sole as the insert 304 is shown in FIGS.13-14.

FIG. 16 shows a sixth embodiment of a resilient shoe insert 500 of thepresent invention. The insert 500 may also be placed inside the shoe300, as shown in FIGS. 13-14, and replace the insert 304 placed insidethe shoe 300. The insert 500 has a slanted straight front-end 502, arounded back end 504 and a narrow mid-section 506. The insert 500 may bemade of a composite material such as continuous fibers that extend fromthe back end 504, such as from the outer end 520, around the front end502 and back to the back end 504, such as to the outer end 522. Thefibers may also merely extend from the back end to the front end.

With reference to FIGS. 17 a-c, the shoe insert 500 has an upper leg 506with a straight upper leg segment 508 that terminates in a concave uppersegment 510. The leg segments 508, 516 may also be slightly concave.Preferably, the segments 508, 516 are less concave than the segment 510.The segment 510 extends to the front-end 502 that is an attachmentsegment 512. The segment may be a curved or pointed segment or any othersuitable shape and the present invention is not limited to a curved orpointed segment. The insert 500 has a lower leg 514 with a straightlower leg segment 516 that terminates in a concave lower segment 518that is adjacent to the concave upper segment 510. The segment 518extends to the front end 502. In this way, the fibers of the insert 500may extend from the upper leg 506 around the curved segment 512 to thelower leg 514. The upper leg 506 has an upper end point 520 and thelower leg 514 has a lower end point 522 that is separated by distance d1from the upper end point 520 when the insert 500 is not compressed, asshown in FIG. 17A. The insert has an effective length 11 that extendsfrom the front end 502 to the end points 520, 522. It is to beunderstood that the shape of the legs 506, 514 may be straight, concave,convex or any suitable shape and the stiffness of the legs 506, 514 maybe the same or the stiffness of the leg 506 may be different from thestiffness of the leg 514.

FIG. 17B shows the insert 500 in a semi-compressed position so that theconcave upper segment 510 is in contact with the concave lower segment518 in a contact segment or point 524. The distance between the endpoints 520, 522 is reduced from the distance d1 to the distance d2 thatis shorter than the distance d1. The effective length of the upper leg506 and the lower leg 514 is reduced from the length 11 to the length 12that is shorter than the length 11. The effective length 12 extends fromthe points 520, 522 to the contact segment 524.

FIG. 17C shows the insert 500 in a compressed position so that the upperleg 506 and the lower leg 514 is in contact over an extended area 526that starts at the contact point 524 and extends backwardly to aseparation point 528. The contact may extend all the way back to the endpoints 520, 522 when the insert is subjected to a sufficiently largeload L. The distance between the end point 520 and the end point 522 isreduced from the distance d2 to a distance d3 that is shorter than thedistance d2. The effective length of the legs 506, 514 is reduced fromthe length 12 to the shorter length 13. Preferably, the insert 500 isplaced inside a shoe, as shown in FIGS. 13 and 14, so that a personusing the shoe may compress the insert 500 as shown in FIGS. 17A-C.

FIG. 18 is a top view of the insert 500 and shows that the effectivelength of the leg on a first side, such as an outside 530, is shorterthan the effective length of the leg on a second side, such as an inside532, of the insert 500. As indicated earlier, the front-end 502 and thecontact segment 524 are slanted at an acute angle alpha compared to thelongitudinal direction L of the shoe insert. The effective length l3therefore varies along the width W of the shoe insert. The effectivelength l₃₀ on the outside 530 is shorter than the effective lengthl_(3i) on the inside 532. This makes the outside 530 of the insert 500stiffer than the inside 532 similar to the embodiment shown in FIGS. 9and 10. The stiffer outside makes the insert 500, and thus the shoe,more stable. Also, the shorter the effective length l₂, l₃ of the legs,the stiffer the insert 500 becomes. In this way, the stiffness is notonly varied by putting load on the insert 500 but the stiffness is alsovaried along the width of the separation segment 528. The angle betweenthe segment 524 and the longitudinal axis L may be varied as shown bythe contact segments 524 a and 524 b. Preferably, the insert 500 isremovable and replaceable from the shoe system should the user needdifferent stiffness characteristics of the insert 500.

FIG. 19 is a schematic graphic illustration of the load L on the x-axisand the distance d on the y-axis. The surprising increase in load L thatis required to further reduce the distance d2 to the smaller distanced3. Very little load L is required to reduced the distance to d2.However a significant load increase is required to further reduce thedistance to d3. The relationship is not linear but exponential.

While the present invention has been described in accordance withpreferred compositions and embodiments, it is to be understood thatcertain substitutions and alterations may be made thereto withoutdeparting from the spirit and scope of the following claims.

1. A method of using a shoe system having a resilient shoe insert,comprising: providing a shoe having a shoe insert disposed inside theshoe, the shoe insert having an upper leg and a lower leg connected by afront end with an attachment segment, the upper leg having an upperconcave segment, the upper leg having an upper end point and the lowerleg having an lower end point that is separated from the upper end pointby a distance (d1), the insert having an effective length (l₁); puttinga first load on the shoe and the insert; compressing the upper end pointtowards the lower end point until a concave the upper concave segment isin contact with a lower concave segment of the lower leg at a contactpoint is being remote from the attachment segment at the front end sothat a loop is formed between the attachment segment and the contactsegment, the contact segment being remote from both the upper and thelower end points; and the upper concave segment being pressed againstand facing the lower concave segment; bending the attachment segmentuntil a contact point is formed when the upper concave segment comesinto contact with the lower concave segment; putting a second load onthe shoe and the insert, the second load being substantially greaterthan the first load; bending the upper leg and the lower leg at thecontact point to form a contact segment that extends from the contactpoint towards the upper and lower end points and terminates at aseparation point to progressively increase a stiffness of the upper andlower legs; the contact segment reducing the effective length (l₁) to aneffective length (l₂), the length (l₂) extending from the contactsegment to the upper and lower end points.
 2. The method according toclaim 1 wherein the method further comprises extending the contactsegment from an outside to an inside, the segment being substantiallyparallel to the front end, the front end forming an acute angle to alongitudinal axis (A) of the insert.
 3. The method according to claim 2wherein the method further comprises further compressing the upper endpoint towards the end point to reduce the distance (d2) to a distance(d3) that is shorter than the distance (d2) and forming a contact areabetween the upper leg and the lower leg.
 4. The method according toclaim 3 wherein the method further comprises shortening the effectivelength (l₂) to an effective length (l₃) at a mid-portion of the contactsegment, the length (l₃) being shorter than the length (l₂).
 5. Themethod according to claim 4 wherein the method further comprisesproviding the insert with an effective length (l₃₀) at the outside, theeffective length (l₃₀) being shorter than the effective length (l₃) atthe mid-portion.
 6. The method according to claim 5 wherein the methodfurther comprises providing the insert with an effective length (l_(3i))at the inside, the effective length (l_(3i)) being longer than theeffective length (l₃) at the mid-portion.
 7. The method according toclaim 1 wherein the method further comprises providing the attachmentpoint with a curvature.
 8. (canceled)
 9. The method according to claim 1wherein the method further comprises aligning the upper concave segmentwith the lower concave segment.